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가공성이 향상된 하이드라자이드 및 옥사다이아졸 고분자의 합성
유지강,이용혁 조선대학교 생산기술연구소 1998 生産技術硏究 Vol.20 No.2
Polyhydrazide는 방향성의 dihydrazide 단량체와 유연격자가 포함된 bisbenzoyl chloride 단량체를 저온에서 dimethylacetamide를 중합용매로, pyridine을 산제거제로 사용하여 용액중합으로 합성하였다. Polyoxadiazole은 polyhydrazide를 thionyl chloride로 처리하는 화학적 고리탈수반응으로 합성하였다. Polyoxadiazole의 희박용액점성도는 0.68㎗/g이었다. 합성된 고분자는 비양성자성 극성용매에의 용해도가 향상되었으며 융점이 271℃로서 용융가공이 가능함을 확인하였다. Polyhydrazide was prepared by low temperature solution polymerization of an aromatic dihydrazide and a bisbenzoyl chloride having flexible spacer in dimethylacetamide containing pyridine as an acid acceptor. The polymer was converted into polyoxadiazole by chemical cyclodehydration with thionyl chloride. The inherent viscosity of polyoxadiazole was 0.68㎗/g. The resulting polymer showed enhanced solubility in aprotic polar solvents and melt-processibility as its melting temperature is 271℃.
유지강,이용혁,김희석,김준섭,박기주,D. Nguyen,A. Eisenberg 조선대학교 생산기술연구소 1997 生産技術硏究 Vol.19 No.1
The dynamic mechanical properties of carboxylated polysulfone ionomers were studied by using DMTA. It was found that at 25 mol% of ions, the ionomer shows two glass transitions: one at ca. 200 ℃ and the other at ca. 235 ℃. It was also found that with increasing an ion content to ca. 37 mol%, a matrix T_(g) shifts to ca. 210 ℃, but a cluster T_(g) remains at the same temperature; however, the sizes of tan δ peaks for each transitions do not change with the ion content. This result means that even at those high ion contents, there is sufficient amount of a unclustered material in the samples, and the increase in the ion content does not increase the volume fraction of a cluster phase. In addition, the difference in two T_(g)s of this ionomer system was found to be ca. 40 ℃, which is smaller than that in poly(styrene-co-methacrylate) ionomer system. This finding implies that in the polysulfone ionomers weak ionic interactions in a multiplet resulting from steric hindrance due to the bulkiness of benzene ring to which the ionic group is attached and the tension on polymer chains surrounding the multiplet due to chain rigidity affect the size and stability of the multiplet significantly.
유지강,이법원,김선일 조선대학교 생산기술연구소 2000 生産技術硏究 Vol.22 No.1
Polyhydrazide was prepared by solution polycondensation of an aromatic dihydrazide, bis (2-hydroxy ethyl terephthalic mono-hydrazido) fumarate (BHF) and an isophthaloyl chloride in N-methyl pyrrolidinone (NMP) in the presence of pyridine as an acid acceptor. The polymer was converted into oxadiazole-containing polymer, POD by chemical cyclodehydration with thionyl chloride. In this work, isophthaloyl chloride was introduced t o enhance solubility. The POD can be dissolved in aprotic polar solvents such as NMP and organic solvents such as chloroform/trifluoroacetic acid (TFA) mixed solvent The POD having molecularly designed structure of the fixed conjugation length shows photoluminescence(PL) at about 440 nm which corresponds t o blue color, and Δλ l/2 is about 80 nm which means it emits relatively pure light.
Dielectric Analysis(DEA)를 이용한 옻칠의 분자완화 및 경화과정에 관한 연구
김현경,유지강,홍진후 조선대학교 생산기술연구소 1998 生産技術硏究 Vol.20 No.2
Curing behavior of oriental lacquer has been characterized using the dielectric analysis(DEA). It was found that the oriental lacquer cured to its hardened state most efficiently at moderate temperature in the presence of air at relative humidities of greater than 70%. In order to study the dielectric properties of oriental lacquer film, various films have been prepared differing curing procedures. The glass transition and secondary relaxation temperatures of ordinary oriental lacquer film were observed at 45℃ and -40℃, respectively. On the contrary, the high temperature cured film showed a secondary relaxation at around -50℃. The relationship between thermodynamic properties and chemical structures has been discussed based or, the analysis of the dielectric relaxation behavior using the Cole-Cole plot and the dielectric relaxation intensity
졸-겔법에 의해 합성한 실리카 졸의 GC 및 GC/MASS 분석
김선일,김준섭,유지강 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.2
The optimal condition for reaction of silica sol at room temperature(25±1℃) was identified when the mole ratio of TEOS : EtOH : H₂0 : HCl was 0.345 : 0.390 : 0.612 : 1.21 x 10^(-3). The equilibrium state reached when the hydrolysis for TEOS was proceeded for 40~50 minutes at the room temperature, and the volume percent of ethanol which was detected from GC column reached to 61.6%. In order to identify the path for the molecular growth of intermediate, hydroxyl group of intermediate was change into TMS by the. TMCS, so that monomer and tetrasilicate were 92% based on the amount of TEOS by the GC/MASS.
Styrene-co-lithium methacrylate ionomer의 기계적인 성질에 미치는 LiCl의 영향
나연화,김준섭,유지강,박기주 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.2
The effect of LiCl salt added to styrene-co-lithium methacrylate ionomer on the mechanical properties of ionomers was studied dynamic rnschanically. When the LiCl salt was added to a 100% Li-neutralized ionomer, the amount of added salt. in the range of 100-300% to ionic groups of the ionomer, did not change the mechanical properties of the ionomers, This implies that the added salt may form isolated LiCl salt aggregates in the polymer matrix. However, when LiCl was added to a 200% neutralized ionomer, the cluster T_(g) shifted to a low temperature and then the sample started to flow. This result suggests that in this case the LiCl salts reside in and near the multiplets, resulting the weakening of ionic interactions between ionic groups in multiplets.
포타슘 술포네이트 폴리스타이렌 아이오노머의 기계적인 성질에 미치는 Crown ether의 영향
나연화,조규성,이법원,김준섭,유지강,박기주 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.1
The effects of crown ether on the dynamic mechanical properties of potassium sulfonated polystyrene ionomer were investigated. As expected, it was found that when crown ether molecules were added to the ionomer, the crown ether molecules interacted with K^(+) cations and weakened the ionic interaction between K^(+)/sulfonate ion pairs of the ionomer significantly. Thus, no multiplets were present, and, in turn, no clustering was found. When the ether was added to interact with 50% of K^(+) cations, weak clustering was observed: the clustering was slightly stronger than that of a 50% neutralized ionomer. From this result, it was speculated that in the 50% neutralized sample H^(+) ⇔ K^(+) cation exchange occurs rapidly between -SO₃H and -S0₃K groups in multiplets. which weakens ionic interactions. In the 50% crown ether-added sample, however, -S0₃- group, instead of -S0₃H, is present, and thus no cation exchange is expected to occur.
스타이렌 아이오노머의 기계적인 성질에 미치는 혼합 양이온의 영향
김희석,나연화,이용혁,이법원,유지강,박기주,김준섭 조선대학교 생산기술연구소 1998 生産技術硏究 Vol.20 No.1
The styrene-co-methacrylate ionomers neutralized with Na +, Ba2 +, and mixed cation of both were prepared. The dynamic mechanical properties of two cation-containing ionomers were measured and compared to those of the ionomers neutralized with only one type of cations. We found that in the ionomers with one type of cations the difference in the type of cation does not change the glass transition temperatures. It was found, however, that the cluster Tg of the mixed cation ionomer is lower than that of the single cation ionomers. Thus it was postulated that in the two-cation system the two cations in a solution have sufficient dynamics to form new type of multiplet containing both cations, which may be slightly bigger than that found in the single cation multiplet. The mechanical properties also imply that the strength of ion interactions in the multiplets of the two cation ionomer is thought to be weaker than that of the one cation ionomers. These two effects are believed to contribute the lower in the cluster glass transition of mixed cation system.
조정대,김희종,최재곤,조병욱,유지강 조선대학교 생산기술연구소 1997 生産技術硏究 Vol.19 No.1
Blends of new thermotropic liquid crystalline polymer(TLCP) with poly(ethylene terephthalate)(PET) were prepared by the coprecipitation from a common solvent. The thermal, mechanical properties and morphology of the blends(2wt%, 5wt%, lOwt% and 20wt% TLCP/PET) were examined. In the blends, liquid crystalline phase did not reveal any significant macrophase separation and thermal degradation at the processing temperature. According to the scanning electron micrograps, the TLCP domains in matrix were found to be more or less finely dispersed with 0.2㎛ to 0.4㎛ in size and interfacial adhesion between the TLCP and matrix polymer was excellent. Results of mechanical property measurement show that modulus of TLCP/PET blend was enhanced with increasing TLCP content.